"Smarter" Antennas That Work in Multiple Frequencies

Overview of Antenna Limitations

While computing and associated radio signal processing technologies have been evolving, antenna technology has not kept pace.
Emerging applications, such as a cognitive radio technology, will require reconfigurable antenna technology that can operate
over many bands.

For several reasons, limitations in antenna performance have limited the effectiveness of evolving radio technology.

Traditional antenna technology is designed to support radio operations over a specific range of frequencies, usually within
a specific band because antennas are most efficient at a specific center (resonant) frequency. They become gradually less
efficient and unusable as a radio is tuned further away from that optimal frequency. Because of that, the performance of antennas
that support two or more frequency bands can be significantly compromised.

As frequencies decrease, increasingly larger antennas are required. An antenna operating on two or more bands is sized to
accommodate the lowest operating frequency, and efforts to further reduce size can reduce performance.

Antennas that provide directional properties (as opposed to omnidirectional antennas) are typically larger, more complex and
mechanically directed. This makes them useful for some applications, but not practical for many others.

Electronically Configured, Steerable Antenna

NIJ-funded research at Utah State University is examining the use of millimeter-sized parts — advanced RF micro-electromechanical
systems — technology in antenna design and construction to address antenna limitations.

Researchers have designed and created prototype antennas that are the first step toward creating electrically reconfigurable
smart antennas — devices that are reconfigurable in real time to operate (resonate) on different parts of the spectrum.

This same technology will also allow researchers to design antennas to be reconfigurable in real time, responding to direction
from a computer to point in a specific direction — a steerable antenna. Steerable antenna technology can be used to improve
the performance in a direction of interest and to “null” antenna performance in a specific direction, allowing avoidance or
creation of interference.

A smart antenna controlled by a computer will allow the antenna to be reconfigured to optimize a wireless link in real time,
adapting to support a radio user’s specific needs. In addition, such technological advances could lead to:

More efficient radios that consume less processing power, thereby extending battery life.

Tunable antennas that can operate over a broader swath of spectrum and support public safety frequencies within a single antenna
architecture.